1. Field of the Invention
The present invention relates to an outer-rotor type engine-operated generator.
2. Description of Relevant Art
In recent years, a multipolar generator having magnets disposed on an inner circumferential surface of an outer-rotor has been used widely as an electricity generating section of a portable generator or the like which produces commercial frequency output by inverter control.
When the outer-rotor type multipolar generator is driven by an engine, the outer-rotor can be combined with a flywheel as a flywheel rotor. In this case, it is unnecessary to provide a separate flywheel in addition to the generator so that the engine-operated generator can be made small-sized in its entirety.
With such a generator, it is fairly difficult to use an ignition device to be attached outside such as a conventional self-trigger ignition device in which a magnet is attached on an outer circumference of the flywheel to extract energy for ignition.
Namely, in case of the outer-rotor type generator, because magnets for generating electricity are arranged on the inner circumferential surface of the outer-rotor, the diameter of the outer rotor can not be made small if sufficient energy is to be obtained, and therefore the outer-rotor becomes large in diameter and its circumferential velocity becomes high. If it is intended to also attach a magnet on the outer circumference of such an outer-rotor, as in Japanese Laid-Open Patent Publication No. Sho 61-40463, it is difficult to ensure a sufficient supporting strength of the outer magnet and the outer-rotor becomes large-sized unnecessarily.
Therefore, if the outer-rotor is also used as a flywheel of an engine concurrently, it is inevitable that a pole of a multipolar electricity generating section on the inner side of the outer-rotor is used for ignition exclusively to extract electricity for an ignition device, as shown in Japanese Utility Model Publication Hei 6-46219. As a result, the ignition device itself becomes complicated and high-priced, and a part of the output of the multipolar electricity generating section, which is capable of generating high output by nature, is sacrificed to use it for ignition.